Fabric cutting machine



Dec. 27, 1960 Filed May 10, 1956 R. L. sJ6sTRoM 2,966,086

FABRIC CUTTING MACHINE 7 Sheets-Sheet 1 ZIO 205 I93 y IN OR W7'7fl/l//////////////;/Ill/ll/l/I/Il/j/l/l/ll/l/ llllllh/Q f Dec. 27, 1960R. L. sJ6sTRoM 2,966,086

FABRIC CUTTING MACHINE Filed May 10, 1956 7 Sheets-Sheet 2 B /3O A a3 s7so gig/84% i TOR. hwivfi 1950 R. L. sJc'J'sTRoM 2,966,086

FABRIC CUTTING MACHINE Filed May 10, 1956 INVHVTOR.

Q jyi T Sheets-Sheet 4 Dec. 27, 1960 s 'c3sTRoM 2,966,086

FABRIC CUTTING MACHINE Filed May 10,1956 7 Sheets-Sheet 5 ZlO Dec. 27,1960 R. L. sJ6sTROM FABRIC CUTTING MACHINE 7 Sheets-Sheet 7 Filed May10, 1956 m F/E. /5

oonbnnno nite States aren't FABRIC CUTTING MACHINE Robert L. Sjostrom,Miami Beach, Fla. Everett Mills, 16th St. at 2nd Ave., Boca Raton, Fla.)

Filed May 10, 1956, Ser. No. 583,993

11 Claims. cr. 83-175) The present invention relates to a device forautomatically cutting continuous lengths of material into selectedindividual pieces along preselected lines. In particular the presentinvention is related to a machine for cutting individual articles, suchas towels, from continuous lengths of material in which the individualarticles are defined by transverse bands of difierent thicknesses thanthe main portions of towels.

In the past, rolls of towelling were normally unrolled on a table andstretched out in a flattened position. With the material in thisposition, an operator would then hand-cut an individual towel from theroll by directing a cutting device across the flattened material at thethin traverse band which defines the edge of the towel. In thisoperation, the operator would pay particular attention to make this cutat exactly the center of the band, so that in the finished towels,uniform margins of thin band sections would appear at each end of eachtowel. The difiiculty with this operation is of course that it requiresat least one operator to perform this hand cutting operation, and'inseveral instancesmay require more than one operator where the towellingmaterial is particularly large.

Until the present, automatic devices for performing this cuttingoperation have not been feasible for the towel material when unfoldedfor successive cuttings will not have the successive transverse bands ofthin material fall in exactly the same location. Normally thesetransverse bands of thin material will be'slightly bowed or positionedat slightly different spots on the cutting table. Such conditions poseproblems which makes prior known transverse cutting devices impracticalfor automatically cutting the toweling.

The present invention however overcomes these problems and providesastructure in which a cutting element is automatically guided across thetowel material along the proper and desired cutting line.

Further, the present invention providesa structure in which individualtowels maybe severed-from the whole length of the towel material alongselected lines and then stacked, with means being provided for repeatingthe cycle automatically to insure a continuous proper cutting of a stackof towels from a continuous length of towel material.

Although reference is made herein to the severing of toweling materials,from a towel roll, the present invention is designed to be used withcontinuous lengths of any fabric or similar thin materials in whichindividual pieces are to be successively severed from a substantiallycontinuous length of material along transverse lines, coincident withcontrasting transverse bands on the towel material. Thus any referenceherein to the processing of toweling material should be considered toapply equally as well to other types of continuous thinfiexible materialhaving successive contrasting transverse bands.

In the present invention, there is in general, provided a structurewhich will feed a leading edge of a continuone length of towel materialover a table surface having and? transparent top section under which islocated a light source extending transverse to the length of towelingmaterial. Means are also provided in this structure to stop the movementof the lengths of towel at a point at which the leading thin band ofmaterial is positioned over the transversely extending light source. Atthis point, toweling material is securely gripped at either side edge,and a cutting blade guided by means which follows one edge of thistransverse band severs the leading towel piece from the length ofmaterial along a line preferably coincident with the center line of thetransverse band. The sensing or guiding means are formed preferably of aphotoelectric circuit in which a photoelectric cell is carriedtransverse to the length of material by a carriage element. Thisphotoelectric cell continually aligns with one band defining edge.Normally these bands are formed of thin dense bands between the towelpieces in the length of material, thus having different lighttransmitting qualities.

It is to be noted that this invention may be operated with other formsof material, as for example, fabric material in which the bands areformed by contrasting color hands. The photoelectric cell is activatedto operate the cutting element to move in either longitudinal directionthrough the cells sensitivity to light passing through the thicker andthinner sections of the towel material with different intensities.

These and other objects of the present invention'will be more clearlyunderstood when considered in connection with the accompanying drawings,in which:

Figure l is a plan schematic view of the invention with certain elementsomitted for clarity of understanding.

Figure 2 is a partially schematic view of the invention with portionsomitted for clarity of understanding taken from the back end of theinvention.

Figure 3 is a perspective fragmentary view of the invention taken'fromthe left side.

Figure 4 is a perspective fragmentary View of a detail showing inparticular the cutting carriage.

Figure 5 is an enlarged detail of an element of the invention.

Figure 6 is a perspective view of the invention taken from the rightside of the machine with the clamping elements for the side of the towelremoved.

Figure 7 is a partially schematic detail of an element shown in Figure1.

Figure 8 is a circuit diagram of thephoto tube circuit.

Figure 9 is a partially schematic detail of a modification of an elementof the invention.

Figure 10 is a circuit diagram ofthe controls for the carriages of thepresent invention.

Figure 11 is a circuit diagram of a modified circuit for a photo tubecontrol.

Figure 12 is a modified circuit of a portion of the circuit of Figure11.

Figure 13 is a modified circuit of a portion of Figure 11.

Figure 14 is a somewhat schematic cross sectional detail takensubstantially along the line 1414 of Figure 1.

Figure 15 is a schematic diagram of the modified version of a portion ofthe circuitry of the present invention,

and,

Figure 16 is a schematic diagram of a modified portion of the presentinvention.

Referring specifically to the figures, there is shown a frame formedpreferably in two sections, in which one section generally indicated as1, is provided to support the cutting carriage and'light transmittingsource and in which the section generally designated 2, supports thecarriage which longitudinally moves the length of fabric.

On frame 1, there is provided a table surface 3, having secured withinit-and formed as a portion of it,.the

'32, one on each chain.

aeeepse transparent glass section 4. Also secured to the frame section 1and positioned above the level of the table 3, is a pair of opposite andparallel frame and guide elements 5 and 6 respectively. In each of theseframe guide elements, there is provided a transversely extending rail 7adapted tosupport either side of the cutting carriage 8. This cuttingcarriage 8 has a supporting frame member 9 in which are secured thewheels 18 which guide this cutting carriage 8 along the rail 7 in atransverse movement. Supported on this frame member 9 by suitable meansare a pair of motors 11 and 12. Secured to the armature of these motors11 and 12, are one-half of the electro-magnetic clutches 13 and 14respectively. The other half of these clutches are secured to oppositeends of the lead screw 15 which is in turn secured in and rotatablysupported by suitable means such as bearings 16 to the frame member 9.Threaded on the lead screw 15is a collar or yoke 17 which in turn hassecured to it a cutter supporting element 18. This cutter supportingelement 18 is adapted to move longitudinally with thecollar or yoke 18by the wheel 19, Figure 3. This wheel 19 is pivotally secured to theside of the supporting element 18 and rests upon the beams 20 whichforms a portion of the frame member 9. This cutter supporting element 18supports the cutting tool generally designed 21.

This cutting tool 21 comprises an operating motor 22 which may have ifdesired a locally positioned ON, OFF switch 90. The cutting motor 22operates the cutting blade 23 which is preferably protected by the apron24. This apron 24, rests when the cutting blade is in a cuttingposition, very close to the glass plate 4. If desired the cutting toolmay be provided with sharpening implements 91 secured in to the.supporting elements 18. Also positioned on the cutting frame and securedto the cutting support element is the photo tube supporting member 25which contains the photo tube 26 directed to receive light signals fromthe fluorescent light tubes 27 positioned directly beneath and parallelto the glass plate 4.

The cutter support element 18 although adapted to move longitudinally ofthe lead screw 15 and in the direction of movement of the towel lengths,is limited in its motion in either direction by the microswitches 28 and29 which operate to disengage the magnetic clutches 13 and 14respectively upon overrunning either direction of the lead screw. Whensaid overrunning occurs, the edges of the support element 18 trips theappropriate microswitch and causes it to operate. The cutting carriage 8is carried back and forth across the length of the towel material,cutting in one direction and returning in the other without cuttingthrough the movement of parallel chain conveyors 30 and 31. Thesecontinuous chain conveyors 30 and 31 respectively, are supportedparallel to one another in the frame elements 5 and 6 respectively bythe gears 32. The cutting carriage 8 is secured to these conveyors fortransverse movement by the securing plates 33 and 34, respectively, withone side of each plate being secured to one of these chain conveyors andthe other to the frame member 9. These chain conveyors 3t) and 31 areoperated simultaneously by the driving shaft 35 coaxially with a pair ofgears V This shaft 35 in turn receives its power from a drive source 36through the chain drive 37, which interengages the sprocket gear 38 withthe motor gear 39. In the cutting movement of the cutting carriage, inthe direction of the arrow A, the cutting blade comes down to thesurface of the glass plate 4. In the reverse movement the'cutting bladeis somewhat moved upward from this glass plate 4 so as to permit alength of towel material to be pulled undereath the blade while it is inits transverse return motion indicated by the arrow B. In the returnmovement of the cutting carriage 8, the blade is raised from the surfaceof the glass plate 4 by the upward rotation of the tongue 41 whichengages the flange 41' of the supporting element 18. This tongue 41 isfixed to the shaft 40, which in turn is rotatably mounted in bearings42. These bearings 42 are in turn secured to the beam 20. One end ofthis shaft 40 extends over the guide channel 43 and has a finger 44fixed at right angles to its end and adapted to engage the surface ofthe channel 43 in the return motion B of the carriage 8. This guidechannel 43 has at end 45, a pivotable runner 46, normally tensioned in adownward position against the lower channel 47 by suitable springmembers, not shown, but which may comprise a leaf opening. At the otherend of this guide channel 43, there is positioned a second pivotablerunner 48 which is pivotably secured in a spring tensioned normallyhorizontal position by means, not shown, but which may comprise a leafspring member. In the movement of the cutting carriage in the cuttingdirection A, the finger 44, which may have a rotatable wheel 44' at itsend, engages by this wheel 44' the lower channel 47 thereby permittingthe cutting blade 23 to assume its lower and cutting position as thecarriage 8 and finger 44 move in this direction beyond the runner 46.Movement in the return no-cutting direction B, will cause the finger 44to be carried upwards by the runner 46 to the upper guide channel 43,and thus cause the cutting blade 23 to assume its upper no-cuttingposition in the movement of the cutting carriage 8 across the towelingmaterial. In the return movement on reaching the end of its movement inthe return direction B, the guide finger 44 moves downwardly over theupwardly tensioned runner 46, until it is beyond runner 46 and restingon the lower'channel 47. In this position the cutting carraige 8 isagain ready for another cutting cycle. Two sets of microswitches 49, 50and 51, 52, are provided on the frame guide element 6. These microswitches are adapted to be engaged successively by the securing plate33. Starting with the motion of the carriage in the cutting direction A,microswitch 49 has no effect as it controls the cutting carriage 8causing it to move in a cutting direction (the direction in which thecarriage is already moving). On continued motion, this securing plate 33engages microswitch 50. This microswitch has the dual function ofenergizing the operative circuit for the electromagnetic clutches 13 and14 and also for energizing a stop and time delay circuit By energizingthe electromagnetic clutches 13 and 14, at this point, they will respondto excitation signals supplied from the photoelectric tube 26, thusmoving the cutting blade in a desired direction as determined by thephoto tube 26. The stop and time delay mechanism (90) is provided topermit the photoelectric tube 26, sufficient time to locate the cuttingblade in its proper initial position prior to the movement of thecutting carriage across the towel material. Ordinarily one or twoseconds should be sufficient. In this operation, towel material, whichis located beneath the cutting carriage 8, has been positioned with itsthin transverse sections 12 of material positioned over the plate 4. Thephotoelectric tube 26 during the time delay interval hunts back andforth until it locates the edge defining the thicker main portion of thetowel material from the thin sections 12 of the towel material. Thehunting motion is caused through the control of the electric magneticclutch circuit (hereafter described), by the photo tube, with theclutches in turn controlling the operation of the motors 11 and 12. Whenthe cutting tube 26 is on the edge, the cutting blade is in turnpositioned at a selected fixed distance from the photo-tube so as tobegin the initial cut at the center of this transverse thin section, ata selected distance from an edge. In order to provide proper adjustmentso that the blade may be moved to the center of these thin sectionswhich may be varied in sizes, the photo-tube is positioned on anadjustable support.

After the selected time delay has elapsed, the carriage 8 is movedacross the towel member by the chain conveyors 31. with the cuttingblade 23 severing the lead jaw member.

ear-ease h piebe of towel from the main portion of the toweling lengthat the thin transverse band. The cutting blade 23 is guided in thisaction by the photoelectric tube which continuously follows the edgetransverse to the length of the toweling.

As the blade approaches the far side of the toweling, the plate 33engages the microswitch 51. This microswitch deenergizes the electricalcircuit through the electromagnetic clutches 13 and 14, thus disengagingthe lead screw 15 and causing the blade 23 to be non-responsive tosignals of the photoelectric tube. This action has been found necessarybecause the tube shortly thereafter moves oft the toweling material anddirectly over the plate 4, where it is subject to a much higherintensity of light. This higher light intensity would otherwise causethe cutting blade to move entirely out of line with the selected cuttingdirection. Since the clutch is deenergized with the blade onlyapproximately 2" from the edge of the toweling material, very little offcenter cutting, if any, will occur in this short distance. Shortly afterpassing over the microswitch 51, the securing plate 33 next engages themicroswitch 52 in the operating motor circuit, which causes the motor,and therefore the carriage 8 to reverse direction and return. returndirection the cutting blade 23 is raised level of the plate 4 by theaction of the finger 44 as previously described. As the carriage in thisreturn movement reaches the other end of it, it trips microswitch 49which reverses its direction and returns the carriage in a cuttingdirection and thereupon starts a new cycle. The towel material isperpendicularly pulled forward by the carriage 58 after the leadingsection is cut. This carriage operates to engage the leading edge of thelength of towel and pull it forward until the subsequent transverse thinstrip of material has reached the position over the plate 4. Thisgripping and pulling action takes place during the return motion of thecutting carriage to an initial cutting position in the direction B. Thecarriage 58 is formed of a supporting bed 59 having wheels 60 pivotallysecured at each corner. These wheels 60 rest on the runners 61 and 62 topermit the carriage to be moved freely and in a longitudinal directionwith relation to the direction of movement of the towel material. Asecond set of wheels 66' below the runners 61 and 62 also secured to thebed '59 serve to secure the carriage in place. Supported on thiscarriage are a pair of supporting arms 63 and 64extending rearwardly andparallel with one another. These arms are each provided with similarclamps 65 at their ends. (See Figure 5.) These clamps consist"essentially of upper and lower jaw members '66 and 67 respectively. Thejaw members of each clamp are pivotally supported by a commontransversely extending shaft 68 with the upper jaw members fixed rigidlyto the shaft 68 and the lower jaw members freely mounted on thembypivotable bearing elements'67' extending upwardly on either side ofthe upper jaw 66. Toeach or" the lower jaw members 67, is secured anupper and lower leaf spring69and 70 respectively. The lower leaf spring70 is adapted to engage the upper surface of the table 3 upon movementor" the carriage 58. This engagement forces the edge of the lower jawmember downward in a pressed relationship with the table top, insuringthe towel member which is to be engaged to be carried above this lowerThe upper leaf spring 69 tensions this lower jaw member so that the rearedge of this jaw memberwill normally pivot upwardly above the levelingtable 3 when the lower spring 70 is not engaged. The purpose of thisupper leaf spring is to insure that the leading edge of these jaws 67will not jamb against the side of the table 3 but rather will alwaysclear it. 'After the jaw 67 has cleared the table, the spring 70 willcause the jaw to move downwardly against the top as described.

The upper jaws of each of the clamps are simultaneously controlled 'by'a solenoid 71 fixed to'the carriage.

In its This solenoid 71 (see Figure 7),'operating through the lever arm72 and arm extensions 73 and 74, when actuated, will raise the upper jawelements to permit the leading edge of toweling material to pass betweenthe jaw elements. This solenoid 71 is electrically controlled in itsoperation by the switches 75 and 76. Each of these switches are engagedby the elongated arm 77 fixed to the carriage. Switch 75 is actuatedduring movement from the table '3 or the forward movement of thecarriage 58 by this elongated arm 77, to energize the solenoid 71 andthereby open the jaws from their normally closed position. This willrelease the towel which has previously been secured between the jawelements. On its rearward movement, or movement toward the table 3, theelongated arm 77 engages the switch 76. This engagement which occursover a time interval will energize the normally closed clamps 65 to anopen position as they pass over the table, so that the leading edge ofthe towel material may be sandwiched between the upper and lower jawmembers of the clamps. As soon as this leading 'edge is so positioned,the elongated arm 77 will have passed over the switch 76, thus causingit to deenergize the solenoid '71 andthereby permitting the jaw membersto close 'on theleading edge of the towel. The carriage will then 'onits forward motion carry with it the towel member drawing it forward toa selected position determined by the location of switch 75. The fartherswitch 75 is positioned from the plate 4, the greater arnount of towelmaterial is drawn out. By properly selecting location of the switch 75,the transverse band of thin material may be approximately located in itsproper position on the plate 4.

As the toweling material when drawn out by the carriage 58 has thetrailing edge of the cut piece about to be cut, resting over the glassplate '4, and a portion of the table 3, it is necessary to insure aprompt removal of this tail end from this surface prior to the movementof the carriage 58 over the glasspla'te and the tabletop during thesuccessive cycle. In order to assure that this tail end of the severedpiece is promptly removed, an air dolfer system is utilized inconjunction with the synchrono-us operation of the carriages 58 and 8.Thisair dofier system comprises essentially a perforated tube 13%positioned parallel to the table top 4 and'at a position slightly abovethis top andabo've the toweling material which is drawn through. Itshould also be positioned sufficiently high so as not to interfere withthe movement of the carriage 58. This tube is provided with perforationsdirected downwardly towards the point at which the toweling materialpasses over the edge of the table. This tube 130 is closed at one end131 and has connected to it a tube 132 providingair pressure ofsufficient force to blow the toweling material downwardly oh the table.This air pressure is intermittently admitted to the tube 130 through asolenoid operated valve 133. This solenoid operated valve 133 will openonly after a out has been completed on the toweling material and priorto the return of the carriage 58 for the next cutting cycle. The valve133 and its operating solenoid may be controlled by a microswitchpositioned on the frame supporting the carriage 8 and may be actuated bythis carriage on its return movement.

When the length of the toweling has been drawn over the plate 4 and isready for cutting, it is secured in position on either side by two setsof clamp members 53 and 54. Clamp member 53 comprises a pairof paralleljaws Tilt and liil pivotally secured to the table 3 at one end by pivotelements 102 and 103. Each jaw is operatively connected to a solenoid(not shown) below the table at positions 194 and 165. These jaws arenormally tensioned in an up or open position and are closed throughenergizing the solenoid just prior to the cutting operation. Theclamping member 54 is designed not only to hold the towel material downagainst the table 3, but also to draw it outwardlyof the table inanemone order to stretch it and straighten to some extent the transversebend of material through which the cut is to be made. 'By this means theamount of hunting required of the photo tube 26 is reducedsubstantially.

The clamp element 54 comprises a pair of opposite jaw members 190 and191. These jaw elements are interconnected by a pair of shafts 192 and193. Pivotally extending from the shafts at each end are pairs of leverarms 194 and 195. These lever arms are pivoted at their other end bycross member 196which is also pivotally supported on cross members 198and 199. Pivotallv extending from these cross support members 198, 199are two additional sets of lever arms 200 and 201 which have pivotallysecured at their upper end an additional cross member 202. Thisrcrossmember 202 is also positioned on cross support shafts 203 and 204. Apair of springs 205 interconnect cross supporting shafts 198 and 193. Alever arm 206 pivoted on the shaft 35, interconnects the shaft 207 ofthe push solenoid 208 with the end of member 202. These may be linkedtogether at 209 in such a manner that when the solenoid 208 is actuatedand moves the shaft 207 upwardly, the jaws 190 and 191 operating throu hthis lever system Will move downwardly and outwardly towards thesolenoid 208 thus drawing any toweling material positioned below themoutwardly and simultaneously force the toweling material downwardagainst the table top 4.

A second modification of this clamp member 54 is illustrated in Figure9. where there is shown schematically a clamp member having identicaland parallel arms 120. These arms 120 are pivotally secured by the pivotelements 121 to the table top 3. Each arm is provided with a contactelement 122 longitudinallv slid ble on the arm 120. The arm 120 isnormally tensioned in an up posi ion by the spring 123, preferably coxial with a shaft 124 which interconnects the arm 120 with the solenoid125. This solenoid 125 when actuated will act against the tens on of thesprin to close the arm 120 downwardly. The contact member 122 isconnected to a solenoid 126 by means of a wire or cord 127. The solenoid126 is actuated to pull this cord 127 downwardly on the downwardmovement of the shaft 124. Thus in the operation of this modification,when the solenoid 125 is actuated and thereby closes the arm 120, thepin 128 on this shaft 124, will in its downward movement, close thecircuit of the solenoid 126. thus causing a subsequent movement of thecontact 122 outwardly of the table. By proper positioning of theseelements, the contact 122 will move outwardly as it comes in contactwith the table surface or comes close to the table surface 3. Thus atoweling material positioned between the contact 122 and the tablesurface 3, will be simultaneously secured between these elements anddrawn outwardly towards the edge, thus providing the necessary stretchof the transverse band of material.

The carriage 58 for moving the toweling material longitudinally of thecarriage 8 are operated in synchronism from a common power source. Thusthe carriage 58 is secured by arm members 78' to the chain conveyors 78and 79. These conveyors 78 and 79 are located on either side of theframe section 2 and are suitably supported by sprocket and idler gears79'. These chain conveyors 78 and 79 are operated from a common driveshaft 80, through chain couplings 80' which shaft 80 in turn isconnected to the motor 81 through a suitable chain and gear coupling 82and gear box 83. Also operated from this motor 81 is the chain drive 37for the cutting carriage. By proper selection of gear ratios, thesecarriages 58 and 8 may be simultaneously and synchronously moved overselected distances. It should also be noted in the structure that themotor 81 may if desired be a hydraulically operated motor so that bothcarriages will accelerate to maximum speed at a uniform rate, which inturn will of course reduce any unnecessary wear and tear on the unit.

In Figure 10 there is illustrated a schematic diagram of the circuitutilized to control the operation of the motor 81 and the magneticclutches 13 and 14. In this circuit, microswitches 49 and 52 controlrespective relays and 136. These relays operate switches 137 which areconnected on the lines 138 and 139 respectively. Dependent upon whichrelay has last been actuated, the switches 137 will connect the lines138 and 139 to the power source 140 to operate the motor 81 in aselected direction of rotation. Thus the lines are arranged to cause themotor 81 to operate the cutting carriage in the direction A whenmicroswitch 49 is actuated and in the direction B when microswitch 52 isactuated. Microswitches 50 and 51 are connected to a relay such as thedifferential relay 141 which operates to open and close switch 142dependent upon which of the microswitches 50 and 51 has been actuated.If microswitch 51 has been operated, the switch 142 is opened and thecoils 143 and 144 of the magnetic clutches 13 and 14 are deenergized.'If microswitch 50 is actuated, the switch 142 is closed and power issupplied to the coils for the purposes previously described. Microswitch50 is also connected to and operates delay mechanism 90. Power to thesemicroswitches may be supplied by conventional means as is the case inother circuits when it is not specifically shown.

In Figure 8 there is illustrated a circuit for operation of thephoto-tube. In this circuit photo-tube 26, is maintained at a suitablebias and has its plate suitably connected to a grid of an amplifier tube151. This amplifier tube is maintained at a proper bias determined bythe light intensity on the phototube 26 by the bias control 152 in thecathode circuit of this amplifier. The output of this amplifier isconnected to the grid input of the tube 153. This tube 153 furtheramplifies and also malntains this input signal at a selected bias. Thetube 153 acts as an analyzer and thereby feeds a signal to the coils 154which will operate to close the switch 156 of the clutch circuit ineither direction, dependent upon the magnitude of current passingthrough the coil 154. This switch 156 may be connected into the circuitof Figure 10-as indicated. In Figure 8 there is shown typical values forthe various resistors and bias voltages which may be used in thiscircuit as well as tube types.

Figure 11 shows a further modification of the electrical circuit bywhich the phototube 26 operates the cutting implement. In this circuitan exciter section 158 provides an input D.C. bias to the bridge circuit159. This bridge circuit 159 has the photo-cell 26 formed as one leg ofthe bridge, with a balancing resistor in the opposite leg. The output ofthis bridge circuit 159 is fed into a comparator circuit 160. Thiscomparator circuit 160 separately amplifies the signals of differentpolarity received from the bridge circuit 159 and feeds these amplifiedsignals through a blocking condenser 161 into the amplifier section 162.The signal when amplified is then fed from this amplifier section 162into one of either of the thyratron tubes 163 or 164, depending upon thepolarity of the error signal. These thyratron tubes are connected intothe circuit for operating the clutches and have connected to them inelectrical series the transformer coils 143 and 144 respectively.Depending upon the particular tube fired, current will pass in thecircuit of either coil 143 or coil 144 thus causing one or the otherclutch to engage and operate the lead screw in the selected direction.This modification is of particular advantage as the instantaneous actionof the thyratron tubes aid substantially in cutting down theover-running of the lead screw.

In this circuit when a proper balance is obtained and the photo-cell ison the line which determines the thicker 7 from the thin section, aproper balance is obtained and agaeepsci fied on one or the otherhalf'of the comparator and then fed throu h a secondstageamplifier'intothethyra tron section as described.

It should be noted that the thyratrons are arranged in phase oppositionfor proper operation of this circuit. Various resistors and condensersnot specifically explained are conventional for balance, blocking andsimilar purposes. In Figure l2'there is shown. a modification of thecircuit of Figure 11, in which the output error signal derived from theplate'of tube 162 is fed into the gr.d inputs of the thyratrons 171and172. These thyratrons which are in phase opposition with one another,conduct on signals of opposite polarity derived fromthe error signalsource. If thyratron 171 is conducting it will cause a current to fiowin the coils of transformer 173 and if thyratron 172 is conducting itwill cause current to flow in the coils of the transformer 174. Thesecondary of these transformers 173' and 174 are con nected in serieswith the opposite phases of the two phase motor 175. Thus, dependinguponthe'tube which is conducting, either phase of the motor 175 willcause'it to rotate in a direction opposite to the direction of operationby the other phase. 3.75 is substituted for the pair of motors Hand 12;Further this modification permits the elimination of' the clutchmechanism previously described'andaltows a direct motor control andoperation of the lead screw. This structure is of substantial benefit inavoiding the problems of overrunning caused by the characteristics ofthe clutches. In this modification almostinstantaneous response isobtained thus minjmizing. the amount ofhunting and overriding of thelead screw.

A further modification of the invention is illustrated in Figure 13,which illustrates a modification of the thyratron cIrcuit illustrated inFigure 11 from the output of the amplifier tube 162. In thismodification the error is fed through transformers 18001 181. Current intransformer 181 is fed into the thyratron 183. These thyratrons whichare analyzed in phase oppositionoperate to pass current through thetransformers 185 and 184 respectively. These transformers supply powerto the DC. motor 186 in opposite polarity, causing it tooperate inopposite directions depending upon the transformer through which thecurrent is being passed. When a signal is obtained in either one of thethyratrons, the motor begins to operate in a select direction. As themotor is electrically connected to the cathode of the tube, it acts toraise the bias of this cathode and thus as the lead screw begins toaccelerate to a constant speed, the bias on the cathode increases. Afterit reaches a constant speed, the input signal decreases and the biaswill remain approximately the same until the thyratron cuts ofi. Thisaction occurs in opposite phase in either tube depending upon thedirection of rotation. By this action the motor 186 will be deenergizedslightly before a zero error thus providing an additional means foravoiding or minimizing hunting and overrunning.

A further modification of the electrical circuit of the presentinvention is shown in Figure 15. In this circuit the photo tube 300detects a change in density in the toweling passing under it, andthereby changes the bias on the grid 301 of the tube 302. This change inbias is amplified and inverted and applied through the line 303 to thegrid of thyratron 304. An input to the grid of this thyratron causes itto conduct thus engaging the clutch 305. A portion of the signal derivedon the plate 306 of the tube 302 is fed back into the grid 307 of thetube 302 through the resistor 310. This is in turn amplified andinverted and fed into thyratron 309. Depending upon the balance 310 andthe bias level of the thyratrons 3-3-4 and 309, either clutch 305 or 311may be engaged.

Because of the characteristics of the clutches involved including theinertia, time lag and inductance characteristics, the clutches areplaced in the plate circuits of the thyratrons. The circuit indicated at315 in Figure 15 In this modificat-i'on the motor provides. a: laggingA.C. bias to .the'thyratron grid,

thus allowing a measure of proportional control of the cluthces. This inturn results in a smoother operation and greater accuracy of theelectrical circuit.

This circuit is connected at points C and D, indicated in both portionsof Figure 15.

In Figure 16 there is shown a schematic modification of a portion of theinvention. In this schematic modification, provision is made for theoccasional section of toweling in which the thin section 330 of thetoweling 331 is much wider than the usual thin section. This generallyoccurs approximately every fiftieth towel when the continuous lengthsarestitched together. In this modification'an additional photo tube 332 ismounted on the carriage 8, upon which is also mounted the cutting blade23. This photo tube 332 detects the light differential through thetoweling 331 with the light being derived from the fluorescent tube 333.The signal thus derived is fed into a suitable amplifier of the typepreviously described 334 where a signal is-derived capable of operatingthe solenoid 335. This solenoid 335 controls the opening of the jaws ofthe clamps 65. Thus in the operation of this circuit, as the toweling331 is drawn forward by the jaws 65, the phototube 332, will detect theleading edge of the thin portion. When this occurs a signal will bederived which will cause the solenoid 335 to open the jaws of the clamps65, thus stopping the toweling with the edge of'the thin sectionpositioned below the photoiube 332. The cutting blade 23 may then cutthe section in a manner as previously described. If the blade 23 isclose to the phototube 332, and just behind it, this cut will leave thelarger thin section of the toweling 331 on the section of toweling dueto be cut on the next cycle. This section of toweling, may subsequentlybe removed by hand operation when the towels are hemmed. Thismodification however, provides means for maintaining a continuity ofoperation despite the intermittent occurrence of the wider sections ofthin material 330, or variation of length of toweling between the thinsections.

Other types of photo-tubes than those mentioned previously may also beused and adapted for the present invention. Thus, photo-tubes whichdetect light reflection may be used provided sufiicient light contrastmay be detected upon the material being processed. Thus in certainapplications the phosphorescent tubes beneath the glass plate may beeliminated.

It is further noted that the present invention may be used to processmaterials other than fabrics.

I claim:

1. A machine for severing individual pieces from a continuous length offabric at successive transverse defining lines on said length, havingmeans for advancing said length of fabric, cutting means for severingsaid pieces at said line, and photoelectric means for guiding saidcutting means including a photo tube and light source photoelectricallyresponsive to light differentials on either side of said line, andcarriage means for conveying said photoelectric and cutting means acrosssaid fabric whereby said photoelectric means may track and said cuttingmeans may sever said fabric at said line.

2. A machine for severing individual pieces from a continuous length offabric at successive transverse defining lines on said length, havingmeans for successively advancing said length of fabric, cutting meansfor successively severing said pieces at said lines, means fortransversely moving said cutting means, means in its transverse movementacross said length of said fabric, for moving said cutting meanstransversely of its path of movement and means, including a lightdifferential detecting means for detecting light differences on eitherside of said line and for controlling said means for moving transverselyof its path of movement to follow said line during its movement acrosssaid fabric.

3. A machine for severing individual pieces from a continuous length offabric, having transverse bands of apnoea different light transmittingqualities, having cutting means for transversely severing said piecesfrom the length, light difierential detecting means for detecting lightdifferences in adjacent bands, means for tracking said detecting meansover said fabric at the edge of said bands, with said cutting means in afixed relationship to said detecting means whereby said fabric may besevered along a line determined by said edge.

4. A machine for severing individual pieces from a continuous length offabric having transverse bands of difierent light transmittingqualities, having a plate, means for advancing the edges of successivebands to positions of rest over said plate, tracking means including acarriage adapted to be moved over said plate having secured thereto alight detecting device adapted to detect light variations on either sideof the said edges and a cutting device for cutting said fabric on a linedetermined by said edge, and means for transversely moving said carriagein synchronism with said advancing means.

5. A device as set forth in claim 4, wherein said plate is transparentand a light source is positioned longitudinally of and below said platewhereby said detecting device is activated by light emanating from saidsource.

6. A device as set forth in claim 4, wherein said means for advancingthe edges of successive bands comprises a carriage adapted to movelongitudinally of said length with a rearwardly projecting clamp memberhaving lower and upper jaws, means adapted to tension the lower jawsagainst the plate and the upper jaws open when said carriage movesrearwardly over said plate towards the leading edge of said length andadapted to close said jaws as the carriage moves forwardly.

7. A device as set forth in claim 4, wherein said means for advancingthe band edges comprises an advancing carriage having clamp members forgripping the leading edge of said length and operating means for saidcarriages adapted to cause alternate cutting and advancement of saidlength of fabric.

8. A device as set forth in claim 4 wherein said length of material maybe secured over said plate during the cutting operation comprisingfinger members at opposite sides of said plate and adapted to bepositioned over said length, and means for closing said fingers towardsaid plate during the time interval said bands are positioned at restover said plate.

9. A device as set forth in claim 4, wherein said length of material maybe secured over said plate during the cutting operation comprising apair of clamping members positioned at opposite sides of said plate andadapted to be positioned over said length, means for closing saidclamping members toward said plate and applying an outwardly directedtension on said length on the portion over said plate whereby said bandsmay be held in a flat stretched position during said cutting operation.

10. In a device for severing individual pieces from a continuous lengthof fabric having transverse bands of different light transmittingqualities, photoelectric means for detecting the edges of said bands fortracking purposes, means mounting the photoelectric means for selfguiding tracking along the edges of said bands and means for operativelymoving said last mentioned means across the fabric including delay meansfor delaying the moving until said photoelectric means has detected thedesired edge.

11. In a device for severing individual pieces from a continuous lengthof fabric having transverse bands of different light transmittingqualities, with a severing element guided in successive cycles byphotoelectric means detecting the edges of said bands, a delay means fordelaying the severing during each cycle until said photoelectric meanshas detected an edge of said band.

References Cited in the file of this patent UNITED STATES PATENTS1,561,403 Botcher Nov. 10, 1925 1,619,940 Kaplan Mar. 8, 1927 1,984,804Newmair Dec. 18, 1934 2,261,644 Cockrell Nov. 4, 1941 2,341,011 BascomFeb, 8, 1944 2,445,041 Scholz July 13, 1948 2,479,293 Baylcss Aug. 16,1949 2,546,831 Newell Mar. 27, 1951 2,581,937 Secrest Jan. 8, 19522,643,720 Miles June 30, 1953 2,665,757 Stevens Jan. 12, 1954 2,705,443Colby Apr. 5, 1955 2,738,007 Power Mar. 13, 1956 2,859,813 Klotz Nov.11, 1958

